The purpose of this longitudinal proposal is to continue the investigation of a near total county population of white male elementary school children (N equals 497) who were tested at the beginning of kindergarden (Fall, 1970) and a cross-validation sample of similar children (N equals 180) who were tested at the beginning of kindergarten (Fall, 1971). Because of active cooperation and participation of the county school system, virtually all of the original standardization group (96 percent) and cross-validation group (100 percent) are still involved in the project. The general purposes of the project are threefold: (1) to evaluate the predictive validity and utility of the test variables, given to 1970, against the criterion of reading achivement in 1973 and 1974 (early detection problem), (2) to determine whether performance on these developmental measures change differentially as the disabled and average readers become older (Developmental Lag Problem) and (3) to determine the relationship, if any, between specific reading disability and precursors more remote in time (e.g., neurological birth status and familial reading problems). The current project is addressed to nine temporal objectives in order to investigate the preceding problems: (1) administration of the criterion reading measures in 1973 and 1974 (Criterion 2), (2) criterion group identification (base rate incidence of dyslexia), (3) predictive and cross-validation analyses to Criterion 2, plus restandarization (1974-1975), (4) readministration of standard test battery (Retest 1) to total standardization and cross-validation sample in 1973 and 1974, (5) selection of matched control subgroup of average readers (C) with total group of disabled readers (E) in 1974, (6) neurological examinations to groups C and E (1974-1975), (7) investigation of birth history data and familial reading levels between groups C and E (1974-1976), (8) readministration of standard test battery (Retest 2) and criterion reading measures and (9) evaluation of theory on developmental changes postulated to occur between groups.